Silica sol is a colloidal solution of a nanometer-order inorganic poly-metasilicic acid with water as a dispersion medium; during use, it may be used in film forming as an independent film-forming substance, but problems like cracks of a certain extent will occur after the film forming, which affects continuity of the film layer. In order to improve the film-forming performance of silica sol, film-forming auxiliary is usually directly added into the silica sol so as to facilitate its film-forming.
However, when the film-forming auxiliary is directly added into the silica sol, a series of problems will occur, wherein one important problem thereof is the stability of the film-forming auxiliary and the silica sol. The silica sol is a thermodynamic instable system that relies on electrical charge or some other stabilizers to facilitate dispersion; during a compound procedure, it likely causes flocculation, agglomeration or gol due to change of the environment conditions; therefore, the film-forming additive should have a good compatibility with the silica sol. Thus selecting an appropriate film-forming auxiliary is particularly important. Besides, addition of other additives in the system including the film-forming auxiliary and silica sol will facilitate the stability of the film-forming auxiliary and silica sol system; meanwhile, it will also facilitate the continuity of the film forming after the film-forming silica sol is dried. In view of the above, it is significant to develop a film-forming silica sol with a good stability so as to apply it in wider areas.